From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8B7842E7F20; Mon, 13 Oct 2025 07:23:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.19 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760340201; cv=none; b=oO163c+lz0fmXS2K6saip4JFF5pK3B09Tsl6ALDNCGjlNv8f/kKQoSHBd2OzbPCy7x9/1BJnVoup3gRlxeoRxVHymXZJUKezH7pKS6LB5q0zpgB/nkyzh0Kiesr6TyOgSs2OMIiyE7enPy0AK5HBimJBI9dN2rbKGuQbfnrrJZw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760340201; c=relaxed/simple; bh=5rYjsN5XeOyunE3PUJZcaBEskdY9kWOsawHLMQzQslQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=tcw+R9bVVn+JuDtAAYC/1xAuXObijz2hKFn3nA2NkFOtBdUAohoDK2OXTWrody7OKCwdSWpBuE1tOnMgRMtx4oGlIJbZsabvCkoiVrCLwG0g0t9fTxiZvRPrBs3ZE6m6ooZ86GJ7Ls9bDZn3VYWOoNF5/cvsmk/kJmilVqa3LZk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=aFxJ3RYe; arc=none smtp.client-ip=192.198.163.19 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="aFxJ3RYe" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1760340199; x=1791876199; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=5rYjsN5XeOyunE3PUJZcaBEskdY9kWOsawHLMQzQslQ=; b=aFxJ3RYe+JpT5PtCZtf6A9mVVwtUh5ZANsotILAgPvpMU6p0616N/Q02 6zxN0sHx2AKlGVQrFOakLQqvXkcy/UU1gKoFXtlgA/mHeI1ojzBkaBV9Y xILGsCvXABfbkQXJGpPGt79T/JiZeQSqlXLiNs/htLyNMxbp9UkkaBuWV trl0Cy7uG4Yq/VtC5p4aYIsCgoY20a3a0llGGLKvZkDoM9vKosdLB0+W9 sUC25eUvqCgT71JF4Mhy+2RNt1oZigZ5p2sLs+nQd+GBdS0/kmGDYl8th M0IzI70Hp9Q8jNbIw51dVPoGexTBlteNqmDvNNcUpQqBSIVkxVgAWAeC6 Q==; X-CSE-ConnectionGUID: /9bP2/SCRkuJPy31QpY77g== X-CSE-MsgGUID: ICFwt8cUQn6RehtxnrBHSw== X-IronPort-AV: E=McAfee;i="6800,10657,11580"; a="61510111" X-IronPort-AV: E=Sophos;i="6.19,224,1754982000"; d="scan'208";a="61510111" Received: from orviesa004.jf.intel.com ([10.64.159.144]) by fmvoesa113.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Oct 2025 00:23:16 -0700 X-CSE-ConnectionGUID: LxgLBrP8Q4Wrhw0ocGu1Ow== X-CSE-MsgGUID: c65J513iRO+SljnR4gx7tQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.19,224,1754982000"; d="scan'208";a="185790523" Received: from bergbenj-mobl1.ger.corp.intel.com (HELO localhost.localdomain) ([10.245.244.25]) by orviesa004-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Oct 2025 00:23:11 -0700 From: Adrian Hunter To: Peter Zijlstra Cc: Ingo Molnar , Alexander Shishkin , Arnaldo Carvalho de Melo , Jiri Olsa , Namhyung Kim , Mark Rutland , Ian Rogers , Mathieu Poirier , Miklos Szeredi , Alexander Viro , Christian Brauner , Amir Goldstein , Edd Barrett , Laurence Tratt , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org Subject: [PATCH RESEND 3/3] perf/core: Fix MMAP2 event device with backing files Date: Mon, 13 Oct 2025 10:22:44 +0300 Message-ID: <20251013072244.82591-4-adrian.hunter@intel.com> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20251013072244.82591-1-adrian.hunter@intel.com> References: <20251013072244.82591-1-adrian.hunter@intel.com> Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Organization: Intel Finland Oy, Registered Address: c/o Alberga Business Park, 6 krs, Bertel Jungin Aukio 5, 02600 Espoo, Business Identity Code: 0357606 - 4, Domiciled in Helsinki Content-Transfer-Encoding: 8bit Some file systems like FUSE-based ones or overlayfs may record the backing file in struct vm_area_struct vm_file, instead of the user file that the user mmapped. That causes perf to misreport the device major/minor numbers of the file system of the file, and the generation of the file, and potentially other inode details. There is an existing helper file_user_inode() for that situation. Use file_user_inode() instead of file_inode() to get the inode for MMAP2 events. Example: Setup: # cd /root # mkdir test ; cd test ; mkdir lower upper work merged # cp `which cat` lower # mount -t overlay overlay -olowerdir=lower,upperdir=upper,workdir=work merged # perf record -e cycles:u -- /root/test/merged/cat /proc/self/maps ... 55b2c91d0000-55b2c926b000 r-xp 00018000 00:1a 3419 /root/test/merged/cat ... [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.004 MB perf.data (5 samples) ] # # stat /root/test/merged/cat File: /root/test/merged/cat Size: 1127792 Blocks: 2208 IO Block: 4096 regular file Device: 0,26 Inode: 3419 Links: 1 Access: (0755/-rwxr-xr-x) Uid: ( 0/ root) Gid: ( 0/ root) Access: 2025-09-08 12:23:59.453309624 +0000 Modify: 2025-09-08 12:23:59.454309624 +0000 Change: 2025-09-08 12:23:59.454309624 +0000 Birth: 2025-09-08 12:23:59.453309624 +0000 Before: Device reported 00:02 differs from stat output and /proc/self/maps # perf script --show-mmap-events | grep /root/test/merged/cat cat 377 [-01] 243.078558: PERF_RECORD_MMAP2 377/377: [0x55b2c91d0000(0x9b000) @ 0x18000 00:02 3419 2068525940]: r-xp /root/test/merged/cat After: Device reported 00:1a is the same as stat output and /proc/self/maps # perf script --show-mmap-events | grep /root/test/merged/cat cat 362 [-01] 127.755167: PERF_RECORD_MMAP2 362/362: [0x55ba6e781000(0x9b000) @ 0x18000 00:1a 3419 0]: r-xp /root/test/merged/cat With respect to stable kernels, overlayfs mmap function ovl_mmap() was added in v4.19 but file_user_inode() was not added until v6.8 and never back-ported to stable kernels. FMODE_BACKING that it depends on was added in v6.5. This issue has gone largely unnoticed, so back-porting before v6.8 is probably not worth it, so put 6.8 as the stable kernel prerequisite version, although in practice the next long term kernel is 6.12. Cc: stable@vger.kernel.org # 6.8 Signed-off-by: Adrian Hunter --- kernel/events/core.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index 7b5c2373a8d7..177e57c1a362 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -9403,7 +9403,7 @@ static void perf_event_mmap_event(struct perf_mmap_event *mmap_event) flags |= MAP_HUGETLB; if (file) { - struct inode *inode; + const struct inode *inode; dev_t dev; buf = kmalloc(PATH_MAX, GFP_KERNEL); @@ -9421,7 +9421,7 @@ static void perf_event_mmap_event(struct perf_mmap_event *mmap_event) name = "//toolong"; goto cpy_name; } - inode = file_inode(vma->vm_file); + inode = file_user_inode(vma->vm_file); dev = inode->i_sb->s_dev; ino = inode->i_ino; gen = inode->i_generation; -- 2.48.1